[Qemu-devel] [PATCH v5 4/7] tests/docker/dockerfiles: new debian-bootstrap.docker

[Alex Bennée]

Together with the debian-bootstrap.pre script can now build an arbitrary
architecture of Debian using debootstrap. This allows debootstrap to set
up its first stage before the container is built.

To build a container you need a command line like:

  DEB_ARCH=armhf DEB_TYPE=testing \
    ./tests/docker/docker.py build \
    --include-executable=arm-linux-user/qemu-arm debian:armhf \
    ./tests/docker/dockerfiles/debian-bootstrap.docker

Although a number of non-debian systems package the debootstrap script
it is fairly portable in itself. Assuming we have some sort of fakeroot
implementation we can just clone the upstream repository and use the
script from there.

Signed-off-by: Alex Bennée <address@hidden>

---
v2
  - use .pre script instead of embedded HOST_CMD
  - make default image include all QEMU build-deps
v3
  - split docker.py from introduction of bootstrap
v4
  - handle no installed debootstrap [see BTS #830869]
  - add a bunch of pre-requisite checking (fakeroot, binfmt_misc)
  - add mapping from DEB_ARCH to QEMU_BIN
---
 tests/docker/dockerfiles/debian-bootstrap.docker | 21 ++++++
 tests/docker/dockerfiles/debian-bootstrap.pre    | 82 ++++++++++++++++++++++++
 2 files changed, 103 insertions(+)
 create mode 100644 tests/docker/dockerfiles/debian-bootstrap.docker
 create mode 100755 tests/docker/dockerfiles/debian-bootstrap.pre

diff --git a/tests/docker/dockerfiles/debian-bootstrap.docker 
b/tests/docker/dockerfiles/debian-bootstrap.docker
new file mode 100644
index 0000000..3a9125e
--- /dev/null
+++ b/tests/docker/dockerfiles/debian-bootstrap.docker
@@ -0,0 +1,21 @@
+# Create Debian Bootstrap Image
+#
+# This is intended to be pre-poluated by:
+#  - a first stage debootstrap (see debian-bootstrap.pre)
+#  - a native qemu-$arch that binfmt_misc will run
+FROM scratch
+
+# Add everything from the context into the container
+ADD . /
+
+# Patch all mounts as docker already has stuff set up
+RUN sed -i 's/in_target mount/echo not for docker in_target mount/g' 
/debootstrap/functions
+
+# Run stage 2
+RUN /debootstrap/debootstrap --second-stage
+
+# At this point we can install additional packages if we want
+# Duplicate deb line as deb-src
+RUN cat /etc/apt/sources.list | sed "s/deb/deb-src/" >> /etc/apt/sources.list
+RUN apt-get update
+RUN apt-get -y build-dep qemu
diff --git a/tests/docker/dockerfiles/debian-bootstrap.pre 
b/tests/docker/dockerfiles/debian-bootstrap.pre
new file mode 100755
index 0000000..ea12e2c
--- /dev/null
+++ b/tests/docker/dockerfiles/debian-bootstrap.pre
@@ -0,0 +1,82 @@
+#!/bin/sh
+#
+# Simple wrapper for debootstrap, run in the docker build context
+#
+FAKEROOT=`which fakeroot 2> /dev/null`
+
+#
+# fakeroot is needed to run the bootstrap stage
+#
+if [ -z $FAKEROOT ]; then
+    echo "Please install fakeroot to enable bootstraping"
+    exit 1
+fi
+
+# We check in order for
+#
+#  - DEBOOTSTRAP_DIR pointing at a development checkout
+#  - PATH for the debootstrap script (installed)
+#
+# If neither option works then we checkout debootstrap from its
+# upstream SCM and run it from there.
+#
+
+if [ -z $DEBOOTSTRAP_DIR ]; then
+    DEBOOTSTRAP=`which debootstrap 2> /dev/null`
+    if [ -z $DEBOOTSTRAP ]; then
+        echo "No debootstrap installed, attempting to install from SCM"
+        DEBOOTSTRAP_SOURCE=https://anonscm.debian.org/git/d-i/debootstrap.git
+        git clone ${DEBOOTSTRAP_SOURCE} ./debootstrap.git
+        export DEBOOTSTRAP_DIR=./debootstrap.git
+        DEBOOTSTRAP=./debootstrap.git/debootstrap
+    fi
+else
+    DEBOOTSTRAP=${DEBOOTSTRAP_DIR}/debootstrap
+    if [ ! -f $DEBOOTSTRAP ]; then
+        echo "Couldn't find script at ${DEBOOTSTRAP}"
+        exit 2
+    fi
+fi
+
+#
+# Finally check to see if any qemu's are installed
+#
+BINFMT_DIR=/proc/sys/fs/binfmt_misc
+if [ ! -e $BINFMT_DIR ]; then
+   echo "binfmt_misc needs enabling for a QEMU bootstrap to work"
+   exit 3
+else
+    # DEB_ARCH and QEMU arch names are not totally aligned
+    case "${DEB_ARCH}" in
+        amd64)
+            QEMU=qemu-i386
+            ;;
+        armel|armhf)
+            QEMU=qemu-arm
+            ;;
+        arm64)
+            QEMU=qemu-aarch64
+            ;;
+        powerpc)
+            QEMU=qemu-ppc
+            ;;
+        ppc64el)
+            QEMU=qemu-ppc64le
+            ;;
+        s390)
+            QEMU=qemu-s390x
+            ;;
+        *)
+            QEMU=qemu-${DEB_ARCH}
+        ;;
+    esac
+    if [ ! -e "${BINFMT_DIR}/$QEMU" ]; then
+        echo "No binfmt_misc rule to run $QEMU, can't bootstrap"
+        exit 4
+    fi
+fi
+
+echo "Building a rootfs using ${FAKEROOT} and ${DEBOOTSTRAP}"
+
+${FAKEROOT} ${DEBOOTSTRAP} --variant=buildd --foreign --arch=$DEB_ARCH 
$DEB_TYPE . http://httpredir.debian.org/debian
+exit 0
-- 
2.7.4